Laser spot finding

ABSTRACT

Techniques are disclosed for determining the location of laser spot in an image, enabling wind sensing to be performed on captured images of the laser spot. Techniques can include image averaging, background subtraction, and filtering to help ensure that the Gaussian laser spot is detected in the image. Embodiments may include defining a bounding region and altering the operation of a camera such that the camera does not provide pixel data from pixels sensors corresponding pixels of outside the bounding region in subsequent image captures. Embodiments may additionally or alternatively include extracting two stereoscopic images from a single image capture.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims benefit under 35 USC 119(e) of

-   -   U.S. Provisional Application Ser. No. 62/130,349, filed on Mar.        9, 2015, entitled “Stabilized Laser Mounting Technique for        Picatinny Rails,”    -   U.S. Provisional Application Ser. No. 62/131,734, filed on Mar.        11, 2015, entitled “Sniper Multifunction Wind and Range        Measurement with Ballistic Computer,”    -   U.S. Provisional Application Ser. No. 62/137,094, filed on Mar.        23, 2015, entitled “Integrated Wind Laser Rangefinder Receiver,”    -   U.S. Provisional Application Ser. No. 62/137,097, filed on Mar.        23, 2015, entitled “Infrared Laser Spot Finding,”    -   U.S. Provisional Application Ser. No. 62/137,100, filed on Mar.        23, 2015, entitled “Integrated Wind Laser Rangefinder Receiver        ASIC (Application Specific Integrated Circuit),”    -   U.S. Provisional Application Ser. No. 62/137,111, filed on Mar.        23, 2015, entitled “Infrared Laser Bore-Sighting Using Infrared        And CMOS Cameras,”    -   U.S. Provisional Application Ser. No. 62/138,237, filed on Mar.        25, 2015, entitled “Athermalized Optics For Side By Side SWIR        Images Used In Wind Sensing,”    -   U.S. Provisional Application Ser. No. 62/138,240, filed on Mar.        25, 2015, entitled “Clip-On Wind Sensor With Targeting Display        For Snipers,”    -   U.S. Provisional Application Ser. No. 62/138,895, filed on Mar.        26, 2015, entitled “Smart Phone Application For Wind Sensor With        Ballistic Computer And Laser Rangefinder,”    -   U.S. Provisional Application Ser. No. 62/140,147, filed on Mar.        30, 2015, entitled “Peak Detection Optical Receiver System,”    -   U.S. Provisional Application Ser. No. 62/144,230, filed on Apr.        7, 2015, entitled “Integrated Photodiode With Wind Laser        Rangefinder Receiver ASIC (Application Specific Integrated        Circuit),”    -   U.S. Provisional Application Ser. No. 62/144,837, filed on Apr.        8, 2015, entitled “Integrated Riflescope With Integrated Wind        Sensor And Targeting,” and    -   U.S. Provisional Application Ser. No. 62/145,413, filed on Apr.        9, 2015, entitled “Integrated Target Tracking With Wind Sensing        Laser Rangefinder And Ballistic Computer,”        all of which are incorporated by reference herein in their        entirety.

The following regular U.S. patent applications (including this one) arebeing filed concurrently, and the entire disclosure of the otherapplications are incorporated by reference into this application for allpurposes:

-   -   application Ser. No. 15/065,724, filed Mar. 9, 2016, entitled        “Integrated Wind Laser Rangefinder Receiver”;    -   application Ser. No. 15/065,732, filed Mar. 9, 2016, entitled        “Optical Sensor For Range Finding And Wind Sensing        Measurements”;    -   application Ser. No. 15/065,715, filed Mar. 9, 2016, entitled        “Laser Spot Finding”; and    -   application Ser. No. 15/065,701, filed Mar. 9, 2016, entitled        “Riflescope With Integrated Wind Sensor And Targeting Display”.

BACKGROUND

Optical devices such as optical scopes and rangefinders can be utilizedin a variety of applications. In military applications, such devices canbe mounted to weapons to enable tracking of a target and increaseaccuracy in aiming the weapon. Systems utilized by snipers can bring anadded degree of sophistication because many conditions can impactlong-range shots, including range, wind, elevation, and more.Weapon-mounted optical systems can integrate sensors and devices toprovide information regarding these conditions. However, gatheringinformation regarding wind traditionally has been difficult.

Recent technologies have enabled wind sensing to be performed usingstereoscopic laser receivers. Examples of these technologies can befound in U.S. patent application Ser. No. 14/696,004, filed on Apr. 24,2015, entitled “Athermalized Optics For Laser Wind Sensing,” (hereafter“the '004 application”) which is incorporated by reference herein in itsentirety. Such technologies, however, can include components that arevery expensive, may suffer from misalignment due to shock from thefiring of a weapon, may implement bore-sighting techniques can bedifficult and time consuming, and/or suffer from other issues.

BRIEF SUMMARY

Techniques are disclosed for determining the location of laser spot inan image, enabling wind sensing to be performed on captured images ofthe laser spot. Techniques can include image averaging, backgroundsubtraction, and filtering to help ensure that the Gaussian laser spotis detected in the image. Embodiments may include defining a boundingregion and altering the operation of a camera such that the camera doesnot provide pixel data from pixels sensors corresponding pixels ofoutside the bounding region in subsequent image captures. Embodimentsmay additionally or alternatively include extracting two stereoscopicimages from a single image capture.

According to the disclosure, an example method of determining a locationof a laser spot in an image comprises obtaining, from a camera, aplurality of images comprising a first set of images and a second set ofimages. The first set of images comprises images of a scene taken over afirst period of time in which the laser spot is not present in thescene, and the second set of images comprises images of the scene takenover a second period of time in which the laser spot is present in thescene. The example method further comprises combining the images in thefirst set of images to create a first composite image, combining theimages in the second set of images to create a second composite image,creating a difference image by determining a difference in pixel valuesof pixels in the first composite image from pixel values of pixels inthe second composite image, creating a filtered difference image byapplying a Gaussian filter to the difference image, and comparing one ormore pixel values of one or more pixels of the filtered difference imagewith a threshold value to determine the location of the laser spotwithin the filtered difference image.

Embodiments of the example method can include one or more of thefollowing features. The method may further comprise finding a centerlocation of the laser spot, representative of the location of the laserspot within the filtered difference image. The method may furthercomprise defining a bounding region within the filtered difference imagewhere the bounding region comprising a region in which the laser spot isdetermined to be located, and altering subsequent operation of thecamera such that the camera does not provide pixel data from pixelsensors corresponding to pixels outside the bounding region for at leastone subsequent image captured by the camera. The method may furthercomprise determining a size of the bounding region, based on adetermined the size of the laser spot within the filtered differenceimage. The camera may be configured to provide two stereoscopic imagesat a time.

According to the disclosure, an example laser-based optical devicecomprises a camera configured to capture a plurality of imagescomprising a first set of images and a second set of images. The firstset of images comprises images of a scene taken over a first period oftime in which a laser spot is not present in the scene, and the secondset of images comprises images of the scene taken over a second periodof time in which the laser spot is present in the scene. The laser-basedoptical device further comprises a processing unit communicativelycoupled with the camera and configured to obtain, from the camera, theplurality of images, combine the images in the first set of images tocreate a first composite image, combine the images in the second set ofimages to create a second composite image, create a difference image bydetermining a difference in pixel values of pixels in the firstcomposite image from pixel values of pixels in the second compositeimage, create a filtered difference image by applying a Gaussian filterto the difference image, and compare one or more pixel values of one ormore pixels of the filtered difference image with a threshold value todetermine a location of the laser spot within the filtered differenceimage.

Embodiments of the example laser-based optical device can include one ormore of the following features. The processing unit may be furtherconfigured to find a center location of the laser spot, representativeof the location of the laser spot within the filtered difference image.The processing unit may be further configured to define a boundingregion within the filtered difference image, where the bounding regioncomprising a region in which the laser spot is determined to be located,and alter subsequent operation of the camera such that the camera doesnot provide pixel data from pixel sensors corresponding to pixelsoutside the bounding region for at least one subsequent image capturedby the camera. The processing unit may be further configured todetermine a size of the bounding region, based on a determined the sizeof the laser spot within the filtered difference image. The camera maybe configured to provide two stereoscopic images at a time. Thelaser-based optical device may further comprise stereoscopic opticalreceiver configured to focus light on two portions of the camera,resulting in the two stereoscopic images. The laser-based optical devicemay further comprise a laser, wherein the processing unit is furtherconfigured to cause the laser to emit a laser beam that generates thelaser spot. The camera may be a shortwave infrared (SWIR) camera.

According to the disclosure, an example non-transitory computer readablemedium may have instructions embedded thereon for determining a locationof a laser spot in an image. The instructions including computer codefor obtaining, from a camera, a plurality of images comprising a firstset of images and a second set of images, where the first set of imagescomprises images of a scene taken over a first period of time in whichthe laser spot is not present in the scene, and the second set of imagescomprises images of the scene taken over a second period of time inwhich the laser spot is present in the scene. The instructions furtherinclude computer code for combining the images in the first set ofimages to create a first composite image, combining the images in thesecond set of images to create a second composite image, creating adifference image by determining a difference in pixel values of pixelsin the first composite image from pixel values of pixels in the secondcomposite image, creating a filtered difference image by applying aGaussian filter to the difference image, and comparing one or more pixelvalues of one or more pixels of the filtered difference image with athreshold value to determine the location of the laser spot within thefiltered difference image.

Embodiments of the non-transitory computer readable medium can includeone or more of the following features. The instructions may furthercomprise computer code for finding a center location of the laser spot,representative of the location of the laser spot within the filtereddifference image. The instructions may further comprise computer codefor defining a bounding region within the filtered difference image, thebounding region comprising a region in which the laser spot isdetermined to be located, and altering subsequent operation of thecamera such that the camera does not provide pixel data from pixelsensors corresponding to pixels outside the bounding region for at leastone subsequent image captured by the camera. The instructions mayfurther comprise computer code for determining a size of the boundingregion, based on a determined the size of the laser spot within thefiltered difference image. The instructions may further comprisecomputer code for obtaining, from the camera, two stereoscopic images ata time.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this invention, reference is nowmade to the following detailed description of the embodiments asillustrated in the accompanying drawings, in which like referencedesignations represent like features throughout the several views andwherein:

FIGS. 1A and 1B are illustrations of different example configurations inwhich laser-based optical devices described herein may be utilized;

FIG. 2 is an auxiliary view of a laser-based optical device, accordingto an embodiment;

FIGS. 3A and 3B are simplified drawings of example images captured by ashortwave infrared (SWIR) camera and a complementary metal-oxidesemiconductor (CMOS) camera, respectively;

FIG. 4 is a flow diagram of a method of enabling bore sighting of aninfrared laser using infrared and CMOS cameras, according to oneembodiment;

FIGS. 5A-11 are images (inverted to facilitate reproducibility) capturedby a SWIR camera;

FIG. 12 is a flow diagram 1200 and illustrating the general process ofcapturing and processing images to determine the location of the laserspot 530, according to one embodiment;

FIG. 13 is an example of a spatial Gaussian filter (SGF) that could beapplied to a difference image;

FIGS. 14A and 14B are graphs showing pixel values (e.g., luminosityvalues) as a function of pixel numbers in a row of an image in which thelaser spot is located;

FIG. 15 is a flow diagram of a method of determining the location of alaser spot in an image, according to an embodiment;

FIG. 16 is a perspective view of an embodiment of a laser-based opticaldevice;

FIG. 17 is a simplified block diagram illustrating various components ofa laser-based optical device, according to one embodiment;

FIGS. 18A and 18B are simplified drawings illustrating a view from theperspective of a user of a riflescope;

FIG. 19 is a flow diagram, illustrating a method for acquiring data,obtaining a ballistic solution, and providing a ballistic solution to anoptical scope display, according to one embodiment;

FIG. 20 is an embodiment of a stabilized weapon mount for thelaser-based optical device and/or other weapon-mounted devices;

FIGS. 21 and 22 are simplified diagrams of cross-sections of thestabilized weapon mount of FIG. 20;

FIG. 23 is a circuit diagram of an integrated sensor, according to oneembodiment;

FIGS. 24A and 24B are, respectively, simplified cross-sectional andperspective illustrations of an example package into which theintegrated sensor of FIG. 23 may be incorporated;

FIG. 25 is a circuit diagram illustrating how sensors can be utilizedfor laser range finding and wind sensing in a larger device, in oneembodiment;

FIG. 26 is a perspective view of an integrated riflescope, according toan embodiment;

FIG. 27 is a perspective view of an integrated riflescope, according toanother embodiment; and

FIGS. 28A and 28B are simplified cross-sectional views of the integratedriflescope of FIG. 27, according to an embodiment.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any or all of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION OF THE INVENTION

The ensuing description provides embodiments only, and is not intendedto limit the scope, applicability or configuration of the disclosure.Rather, the ensuing description of the embodiments will provide thoseskilled in the art with an enabling description for implementing anembodiment. It is understood that various changes may be made in thefunction and arrangement of elements without departing from the scope.

As provided herein, and broadly speaking, “bore sighting” a laser-basedoptical device to an apparatus means adjusting the laser-based opticaldevice such that a laser of the laser-based optical device illuminates atarget at which the apparatus is aimed. This ensures that range, wind,and/or other measurements taken by the laser-based devices accuratelyreflect measurements taken with respect to the target. A weapon-mountedlaser-based rangefinder, for example, would not provide accurate rangemeasurements of a target at which the weapon is pointed if the aim ofthe rangefinder's laser (used to take the range measurement of thetarget) is not properly aligned—or bore sighted—with the weapon.

Additionally, as used herein, the term “frame” refers to an imagecaptured by a camera. A video camera, therefore, may capture manysuccessive frames in rapid fashion. Thus, the terms “frame” and “image”are used interchangeably herein.

Laser rangefinders and other laser-based optical devices can be mountedto and used in conjunction with another apparatus, such as a weaponand/or optical scope. In military applications, such devices can bemounted to weapons or spotting scopes to enable tracking of a target andincrease accuracy in aiming the weapon. Optical devices utilized bysnipers can bring an added degree of sophistication because they may beable to detect conditions that can impact long-range shots, includingrange, wind, elevation, and more.

Various techniques are disclosed herein for improving the functionalityof traditional wind sensing devices and/or providing for new andimproved wind sensing devices. It will be understood that althoughembodiments describe particular type of laser-based optical devices(e.g., capable of taking wind and range measurements), many techniquesdescribed herein may apply to other types of laser-based optical devicesas well, including rangefinders, optical communication systems, and thelike.

FIGS. 1A and 1B provide illustrations of different example setups inwhich such laser-based optical devices may be utilized in sniperapplications. It will be understood, however, that laser-based opticaldevices may be utilized in other types of setups and in other types ofapplications not illustrated.

FIG. 1A illustrates a setup in which a laser-based optical device 100 ismounted to a weapon 130, such as a sniper rifle or other long rangefirearm. Here, the weapon 130 has an optical scope 110 utilized by auser to aim the weapon at a target, and the laser-based optical device100 is mounted to the optical scope 110. Because the optical scope 110is used to aim the weapon 130, the laser-based optical device 100 maythen be bore sighted with the optical scope 110. In other applicationsand/or setups, the laser-based optical device 100 may be mounteddirectly to the weapon 130, which may or may not have an optical scope.One or more additional devices, such as infrared (IR) adapter 120-A maybe used in conjunction with the laser-based optical device 100 andoptical scope 110. For weapon-based applications such as the one shownin FIG. 1A, features such as mounting hardware and internal componentsof the laser-based optical device 100 and/or other devices may beadapted to maintain their integrity and/or orientation when exposed tothe shock of the weapon being fired.

FIG. 1B illustrates an alternative setup in which the laser-basedoptical device 100 is mounted to a spotting scope 140, which is mountedto a tripod 150 (only the top of which is illustrated). Again, thelaser-based optical device 100 and/or the spotting scope 140 may beutilized with one or more other devices, such as IR adapter 120-B.

FIG. 2 is an auxiliary view of a laser-based optical device 100,according to an embodiment. Here, the laser-based optical device 100 iscapable of taking laser-based range and wind measurements, along withproviding other (non-laser-based) measurements. Other laser-basedoptical devices may provide additional and/or alternative functions thanthose provided by the embodiment shown in FIG. 2. Size, weight, and/orother traits can vary, depending on desired features.

As shown in FIG. 2, this particular laser-based optical device 100 caninclude optics 210 through which a laser light is transmitted andstereoscopic (e.g., right and left) receiving optics 220 through whichreflected laser light is received. The optical device laser-basedoptical device may further include a display, e.g., on a back surface230 of the laser-based optical device 100, to show one or more imagesreceived through one or both of the stereoscopic receiving optics 220,which can direct light toward one or more internal cameras and/or otherphotodetectors, and a control panel 240 with input devices (e.g., one ormore buttons, switches, touchpads, touchscreens, and the like) forproving a user interface through which user input may be received. Theuser may provide input to initiate one or more of various techniquesdescribed herein.

The body 250 of the laser-based optical device 100 and/or componentshoused therein can include any of a variety of materials, depending ondesired functionality, manufacturing concerns, and/or other factors. Insome embodiments, the body comprises aluminum, based on the relativehigh thermal conductivity, strength, cost, relative ease ofcasting/machinability, and/or other concerns. The body 250 may comprisea mountable body configured to be mounted or otherwise coupled to anapparatus, as shown in FIGS. 1A and 1B, and housing (at least partly) alaser, a laser-steering assembly, and a camera, as described in moredetail below. In some embodiments, the body 250 may also house aprocessing unit, also described in more detail below.

General use of the laser-based optical device 100 may vary, depending ondesired functionality. According to some embodiments, the user may boresight the laser-based optical device 100 with an apparatus (e.g.,weapon, optical scope, spotting scope, etc.) to which the laser-basedoptical device 100 is mounted by providing an input (e.g., pressing abutton on the control panel 240) and/or using manual mounting screws, asdiscussed in more detail below. Once the optical device is bore sighted,the user may aim the apparatus toward a target and provide one or moreinputs to cause the laser-based optical device 100 to take measurements,such as determining the range of the target and/or taking laser-basedmeasurements of the crosswind between the laser-based optical device 100and the target. Once the measurements are taken, the laser-based opticaldevice 100 can utilize these measures (optionally with additional data,such as position, tilt, temperature, humidity, etc.), to determine aballistic solution for firing a weapon at the target. The laser-basedoptical device 100 can then display the ballistic solution (e.g., anoffset aim point) on its display and/or on a display (e.g., a displayvisible through the optical scope 110).

Additional information regarding the laser-based optical device 100illustrated in FIG. 2 is provided in the '004 application incorporatedherein above, and U.S. patent application Ser. No. 14/728,133 entitled“Infrared Laser Automatic Bore-Sighting,” which is incorporated byreference herein in its entirety.

Wind sensing generally involves transmitting laser light onto a targetvia the optics 210, receiving the reflected laser light via thestereoscopic receiving optics 220, and comparing the right and leftinputs of the stereoscopic receiving optics 220 to determinescintillations and/or other fluctuations in the reflected laser light todetermine the presence and magnitude of any crosswinds between thetarget and the laser-based optical device 100. Additional informationregarding such wind sensing is described U.S. Pat. No. 9,127,911entitled “Electro-Optic System For Crosswind Measurement,” which isincorporated by reference herein in its entirety. Typically, right andleft inputs comprise camera images of a scene including the target inthe reflected laser light. Thus, determining where the reflected laserlight is within the left and right images can be vital to thefunctionality of the laser-based optical device 100. Furthermore, theseimages can be taken at several hundred per second (e.g., 700 fps, 1000fps, etc.), thus steps can be taken to help facilitate image capture andlaser spot finding at a relatively high speed rate.

According to some embodiments, a laser-based optical device 100 mayadditionally include a CMOS camera, and utilize both short-wave infrared(SWIR) and CMOS cameras to facilitate bore sighting as described below.

Infrared Laser Bore-Sighting Using Infrared and CMOS Cameras

The laser-based optical device 100 and other laser-based devices such asrangefinders, riflescopes, infrared lasers, etc. are required to beaccurately bore sighted for tactical sniper shooting applications. Thatis, lasers emitted by these devices should accurately correspond towhere a weapon (or other device, such as a spotting scope) is aimed.Problematically, however, many laser-based devices used for militaryapplications emit infrared laser beams that invisible to the naked eye.This can make it difficult to bore sight such laser-based devices toriflescopes or other devices.

Using a SWIR camera to determine where the infrared laser is targetedmay not provide sufficient image contrast ratio, particularly when anarrow band sunlight filter is employed to reduce background noise. Ithas been determined, for example, that the location of the laser spotgenerated by an infrared laser in an image captured by a SWIR camera andshown on the display of the laser-based optical device 100 may not beeasily determined with respect to physical features in the image becausethe contrast of the image is so low that the physical features may notbe clearly visible.

To overcome this issue, techniques disclosed herein can utilize both avisible-light (CMOS) camera and a SWIR camera to provide a high contrastimage of the target with a symbolic overlay of the laser spot asdetected by the infrared camera. The use of a separate CMOS camera canenable a device such as the laser-based optical device 100 to use a morerestrictive narrow band sun filter to filter out light from the sun, insome embodiments. This is because the image provided on a display (forexample, the display 230 on the back of the laser-based optical device100 or a display viewable from the eyepiece of a riflescope) is from theCMOS camera rather than the SWIR camera, thereby making the physicalfeatures of the scene more visable. It can be noted that in theembodiments that follow, although a “SWIR” camera is described, thetechniques disclosed herein can be utilized with other types of infraredcameras (and in fact cameras that are configured to capture any type oflight in nonvisible or partially visible EM spectra).

FIGS. 3A and 3B are simplified drawings of images 320-1 and 320-2(collectively referred to herein as 320) captured by the SWIR and CMOScameras, respectively, provided to help illustrate the benefits ofutilizing a CMOS camera for bore sighting. The image 320-1 of FIG. 3Acan represent the image captured by a SWIR camera on a cloudy day.Because a narrowband sun filter removes much of the target imagecontent, overcast days (where there is no direct sunlight on a target)can result in image that has essentially no visible features other thanthe laser spot 330, which is very clearly seen (and detected using, forexample, laser spot detection methods disclosed elsewhere herein). Theoptical path of the light directed toward the CMOS camera, however, mayhave no such narrowband sun filter (or other filter that would reducethe clarity of a visible-light image). This enables the CMOS camera tocapture an image 320-2 with features viewable in visible light. (Otherembodiments may additionally or alternatively employ other filters (orno filters at all).)

The optics utilized to provide both the SWIR and CMOS cameras can varydepending on desired functionality. For example, in some embodiments,light from an objective lens may be split by a beam splitter to divertinfrared light to the SWIR camera in a manner similar to the beamsplitting described in FIGS. 28A and 28B, discussed below, performed bybeam splitter 2870. The diverted light can include a sun filter and/orother filters that may be beneficial to help determine where the laserspot is in the infrared image. The non-diverted light, comprisingvisible light, can then pass to the CMOS camera to enable the CMOScamera to capture an image of the visible light.

An electronic crosshair 340 or other representation can be overlaid onthe image 320-2 captured by the CMOS camera, indicating where, withinthe image 320-1 the laser spot is located. This image 320-1 can be shownby a display of a device emitting the laser and/or shown in a displayviewable through an eyepiece of a riflescope or spotting scope.Accordingly, the crosshair 340 can be utilized to bore sight thelaser-based system to a riflescope or spotting scope.

In some embodiments, the field of view of the CMOS camera can be thesame as the field of view of the SWIR camera. To help ensure that thisis the case, the CMOS camera and the SWIR camera can be co-aligned atfactory during manufacture. If the field of view and resolution are thesame, then it will be easy to determine how the pixels of the SWIRcamera correspond to the pixels of the CMOS camera. If the field of viewand/or resolution of the cameras is/are different, then an offset,scaling, and/or other adjustment factor may be determined during factoryconfiguration to determine how the pixels of the SWIR camera can bemapped to the pixels of the CMOS camera. Once the proper mapping isdetermined, the location of the crosshair 340 (during use of thelaser-based device) in the image 320-1 of the CMOS camera can be easilydetermined depending on where in the corresponding image 320-1 of theSWIR camera the laser spot 330 is detected.

In certain embodiments, a laser-based optical device may include usersettings to enable a user to configure the location of the crosshairs.In such embodiments, the location of the laser spot 330 may beadjustable (e.g., using Risley prisms to adjust the trajectory of thetransmitted laser beam) and/or the position of the crosshair 340 may beadjustable (e.g., by using buttons on a user interface, an applicationof a mobile device connected with the laser-based optical device, etc.)to allow the user to move the location of the laser spot 330 and/or thelocation of the crosshair 340 until they are at corresponding positionswithin each image. In such embodiments, the laser-based optical devicemay further allow a user to toggle between images 320-1 and 320-2 and/orshow both images simultaneously on a display. (As noted above, featuresin the image 320-1 captured by the SWIR camera may be hard to discern oncloudy days. Thus configuration by a user may need to be performed onsunny days or when conditions otherwise allow features to besufficiently shown on the image 320-1 captured by the SWIR camera.)

During use (e.g., during a bore sighting mode of the laser-based opticaldevice) the crosshair 340 can be placed automatically the image 320-2captured by the CMOS camera. The position of the crosshair 340 can becontinuously updated to the display (e.g. at 60 Hz) by software (e.g.,executed by a processor of the laser-based optical device) thatprocesses the infrared camera image and detects the pixel position ofthe laser spot 330 and with appropriate offset, scaling and/or otheradjustments, places the (represented as a crosshair) on the LCD display.

FIG. 4 is a flow diagram of a method 400 of enabling bore sighting of aninfrared laser using infrared and CMOS cameras, according to oneembodiment. It can be noted that, in different embodiments, thefunctionality shown in the illustrated blocks may be different. Othervariations may include combining or separating out the functions ofvarious blocks, performing functions simultaneously, rearrangingfunctions, and the like. A person of ordinary skill in the art willappreciate that various modifications can be made.

The method 400 can be performed by a laser-based optical device, such asthe laser-based optical device 100 of FIG. 2. For example, a CPU orother processing unit can coordinate the functions of method 400 amongvarious electronic components of the laser-based optical device. Suchcomponents can include, for example, a processing unit, a CMOS camera,an infrared camera, and an infrared laser transmitter. Other componentscan vary depending on functionality. Such components may includesensors, communication interfaces, and/or other components, similar tothe components illustrated below in FIG. 17 of a low-cost laser-basedoptical device 1600.

At block 410, an infrared image of a scene is captured. As discussedherein above, the scene can include a laser spot caused by lightreflected from a laser beam. The laser beam can be generated by a lasertransmitter, which may be a component of the laser-based optical deviceperforming the method 400. The infrared image of the scene can becaptured by the infrared camera of the laser-based optical device.

At block 420, of visible light image of the scene is also captured. Tohelp ensure the accuracy of the correlation between images, thefunctions performed at blocks 410 and 420 may be performed atsubstantially the same time. The visible light image of the scene can becaptured by the CMOS camera of the laser-based optical device.

At block 430, the location of the laser spot within the infrared imageis determined. According to some embodiments, the location of the laserspot may be automatically determined using image processing techniques.Examples of such techniques are provided herein below. The location ofthe laser spot within the infrared image may be determined as a pixellocation (for example, an x, y coordinate of a pixel located at thecenter of the laser spot).

At block 440, a location within the visible light image corresponding tothe location of the laser spot within the infrared image is determined.As previously indicated, there may be an adjustment factor to compensatefor differences in the field of view, resolution, or other aspects ofthe CMOS and infrared cameras. Using this adjustment factor, and knowingthe location of the laser spot within the infrared image, the locationwithin the visible light image corresponding to the location of thelaser spot within the infrared image can therefore be determined.

At block 450, the visible light image is displayed with an indication ofwhere, within the scene, the laser spot is located. As previouslyindicated, the indication may be an image such as crosshairs orsomething else (a spot, an arrow, or other indicator). With thisindicator, a user may use the visible light image to bore sight thelaser-based optical device to another device, such as a weapon oroptical scope on which the laser-based optical device is mounted.

Laser Spot Finding

According to some embodiments, techniques may be utilized to determinewhere, in an input image, a laser spot is located. Although describedhere in the context of use with a laser-based optical device (e.g., thelaser-based optical device 100 of FIG. 2), techniques described hereinmay be utilized in other applications where a laser spot is to belocated within one or more images.

FIG. 5A shows left and right images, 510-1 and 510-2 respectively(collectively referred to herein as images 510), captured by a camera ofa laser-based optical device 100. Although images 510 shown here, and inthe embodiments below, were captured using a SWIR camera, it can benoted that the techniques for laser spot finding provided herein can beused on images from CMOS or other visible-light cameras.

Note that the grayscale shown in the images of FIG. 5A-11 has beeninverted (e.g., white is shown as black, and vice versa) forreplicability of the figures.

The scene captured and left and right images 510 is approximately thesame, although there is a slight difference due to the difference inperspective, each of the stereoscopic inputs of the stereoscopicreceiving optics 220. Images 510 were captured while the lasertransmitter was off, therefore a laser spot is not present within theseimages 510. FIG. 5B, on the other hand, shows left and right images,520-1 and 520-2 respectively (collectively referred to herein as images520), were captured while the laser transmitter was on and thereforeshow a laser spot 530. In some embodiments, each of the stereoscopicinputs of the stereoscopic receiving optics 220 may include anarrow-band sun filter to help reduce the amount of sunlight (and otherlight) that is captured by the SWIR camera, which can help ensure thatthe laser spot 530 is the brightest object in the images 520.

The task, then, is to determine where the laser spot 530 is within eachof these images. An initial step comprises background subtraction, forexample subtracting images 520, images 510. This can eliminate staticbackground elements from both sets of figures, making the laser spot 530easier to find. However, there are several issues that typically need tobe addressed in order to find the laser spot 530, even after backgroundsubtraction. Such issues can include, for example, noise caused by deador malfunctioning pixels or movement in the images that can be caused bywind or shimmering. To resolve these issues, embodiments can employvarious techniques such as background subtraction, image averaging, andimage filtering. These issues are described in more detail below.

FIG. 6 shows left and right images, 610-1 and 610-2 respectively(collectively referred to herein as images 610) after backgroundsubtraction has removed static background elements. As can be seen, theimages 610 include not only the laser spot 530, but a large number ofsmaller spots (unlabeled). The smaller spots can be due to dead pixels,which can be a common occurrence in SWIR cameras, given currentsmanufacturing standards. The spots, however, can be eliminated using theimage processing (background averaging and Gaussian filtering)techniques described herein. FIG. 7 shows left and right images, 710-1and 710-2 respectively, corresponding to images 610, but afterimplementing the image processing techniques described below. As can beseen, the smaller spots are substantially eliminated.

FIG. 8 shows left and right images, 810-1 and 810-2 respectively(collectively referred to herein as images 810), again after backgroundsubtraction. As can be seen, the images 810 include not only the laserspot 530, but also one large strip 820 of pixels. The strip 820 ofpixels may be caused by the light shimmering off of a reflectivesurface. Because light shimmers differently at different times, thisstrip 820 may not be eliminated by background subtraction of two frames.However, these strips 820 may be eliminated using the techniquesprovided herein. FIG. 9 shows left and right images, 910-1 and 910-2respectively, corresponding to images 810 after implementing the imageprocessing techniques described below. As can be seen, the strips areremoved.

FIG. 10 shows left and right images, 1010-1 and 1010-2 respectively(collectively referred to herein as images 1010) after backgroundsubtraction. Here, images 1010 include the laser spot 530 as well asareas 1020 having patches of pixels contrasting with the background.These pixels appear after background subtraction due to movement (or“clutter”) in the areas 1020 (e.g., a tree moving due to wind). Again,these pixels can be eliminated using the techniques provided herein.FIG. 11 shows left and right images, 1110-1 and 1110-2 respectively,corresponding to images 1010 after implementing the image processingtechniques described below. As can be seen, the patches of pixels areremoved.

FIG. 12 is a flow diagram 1200 and illustrating the general process ofcapturing and processing images to determine the location of the laserspot 530, according to one embodiment. It will be appreciated that theflow diagram 1200 of FIG. 12 is provided as an example. Alternativeembodiments may add, subtract, combine, separate, or otherwise vary thefunctions shown. It is further acknowledged that, although embodimentsdescribed herein are directed toward finding a laser spot in a pair ofstereoscopic images, embodiments are not so limited. The techniquesherein can, for example, be applied to a single image.

The flow starts at blocks 1210 and 1220 where frames are captured withthe laser off in the laser on, respectively. As shown in FIGS. 5A-5B,image captures should be all substantially the same scene. This canfacilitate subsequent background subtraction. To help ensure thatsubstantially the same scene is captured at blocks 1210 and 1220, theframes captured at these blocks are typically sequential. In otherwords, the camera may capture one large block of frames in which thelaser is on for only part of the time.

To facilitate the subsequent normalization of frames (in block 1230),many frames may be captured. In some embodiments, tens of frames,hundreds of frames, or more may be captured at each of blocks 1210 and1220.

At block 1230, frames are normalized. To be specific, pixel values forthe frames captured when the laser was off (at block 1210) are averagedto create a first composite frame representing frames captured when thelaser was off. Similarly pixel values for the frames captured when thelaser was on (at block 1220) are averaged to create second compositeframe representing frames captured when the laser was on. In so doing,changes in pixel values from one frame to the next caused by noise,movement, or shimmering will be averaged out.

At block 1240, the composite frames are subtracted to create adifference image. That is, the pixel values of the first compositeframes are subtracted from corresponding pixel values of the secondcomposite frame, or vice versa. This provides a background subtraction,removing the background elements that are common between both compositeframes and leaving the few remaining items that are different betweenthe composite frames, such as the laser spot. Because of thenormalization or averaging that took place at block 1230, values ofpixels affected by noise, movement, or shimmering will be similarbetween the two composite frames. Therefore, many of the issues thatarise due to noise, movement, or shimmering will be alleviated in blocks1230 and 1240. As such, these functions serve to increase the likelihoodthat the laser spot 530 will be found within the difference image.

It will be understood that some additional image processing me takeplace. In some embodiments, for example, additional image processing mayoccur to help ensure the composite frames are properly aligned beforethe frames are subtracted in block 1240. Additionally or alternatively,a threshold filter may be applied so the pixels with low values (e.g.,where pixel values of the composite frames were close but not exact) canbe reduced to zero.

At block 1250, a spatial Gaussian filter (SGF) is applied to thedifference image to filter out noise that does not have a Gaussianfootprint. In some embodiments this comprises processing an image row byrow with the SGF that matches an expected to spatial width of the laserspot. Additionally or alternatively, embodiments may the process and theimage column by column in the same manner. Because the laser forms aGaussian laser spot, the SGF is essentially tuned to identify the laserspot within the difference image. To help ensure the laser spot in theimage is Gaussian, the embodiments may alter the integration time of theframe captures in blocks 1210 and 1220 and/or adjust the brightnessand/or adjust contrast of the captured frames so that the capturedimages are not overly saturated.

FIG. 13 is an example of an SGF that could be applied to the differenceimage. Here, the SGF is approximately 20 pixels wide. However, in otherembodiments, the filter may be larger or smaller depending on theresolution of the camera, the expected size of the laser spot, and/orother similar factors. The size of the filter can depend on the size ofthe expected laser spot in the image. Therefore, in some embodiments,the range of the target and or the known diffraction rate of the lasercan be taken into account to determine the width of the SGF. In someembodiments, the difference image may be processed using SGFs ofdifferent widths, to help ensure the laser spot is found. In someembodiments, calibration can be conducted at a given range so that thesize of the laser spot is known. (For example, FIGS. 5A-5B were obtainedat a distance of 500 m, where the laser spot is known to be 4-6 pixelswide—although images may make the laser spot seem bigger due to bloomingand/or saturation effects.) Additionally or alternatively, calibrationcan take place within a known range of distances and different SGFs maybe applied based on the range of possible spot sizes resulting fromcalibration within the known range of distances.

FIGS. 14A and 14B are graphs showing pixel values (e.g., luminosityvalues) as a function of pixel numbers in a row of an image in which thelaser spot is located. As shown in FIG. 14A, a large spot is locatedbetween pixel numbers 4 and 10. However, there are a series ofadditional pixels having high pixel values that follow. FIG. 14B, showspixel values for the same pixel numbers as FIG. 14A, but after the SGFis applied. As can be seen, the larger spot located between pixelnumbers 4 and 10 forms a Gaussian curve, while the smaller spots orsignificantly reduced and value. Thus, the larger spot is the onlylocation in this row of pixels having a pixel value greater than 0.2.Accordingly, large Gaussian in spots may be discovered after the SGF isused by applying a threshold to determine which pixel values are greaterthan and/or equal to the threshold.

Returning to FIG. 12, a threshold is applied at block 1270. In otherwords, the difference image, now filtered by the SGF, is processed todetermine pixels with values that exceed a certain threshold. (In theexample of FIG. 14B, the threshold may be, for instance, a value of0.5.) Given the functions previously performed on the difference image,pixels that exceed the threshold are pixels where the laser spot islocated. In some embodiments, additional precautions may be taken tohelp ensure that it is indeed the laser spot. For example, a location inthe image having a threshold width and/or height of pixels whose valuesexceed the threshold value may be determined.

At block 1280, the determined location of the laser spot is provided. Insome embodiments, the location may be the location of a pixel in thecenter of the laser spot (e.g., a pixel location, by row and column (x,y)). In some embodiments where a stereoscopic optical receiver isutilized, a single SWIR camera may capture left and right imagessimultaneously. Left and right images may therefore be extracted from asingle larger image. In such embodiments, the functions of a process1200 may be utilized to find two laser spots, one for the last image andone for the right image. Such embodiments may additionally provide twooutput locations at block 1280.

As briefly described above, image captured during wind sensing mayrequire a high frame rate. In some embodiments, the frame rate may be700 fps or more. As such, a bounding box may be defined to allow thecamera to only output a portion of the total pixels captured, therebyreducing the amount of bandwidth needed per frame, and increasing theamount of frames the camera is able to output per second. Thus, in someembodiments, once the location of the laser spot is provided at block1280, a bounding box is defined to be large enough to capture the laserspot at different operating distances, and accommodate fluctuations inthe location of the laser spot due to turbulence or other anomalies. Thebounding box is then utilized when the laser-based optical device 100 issubsequently used for wind sensing, where the bounding box defines awindow within an image captured by the camera that will be processed forwind sensing. In practice, extracting wind sensing measurements from abounding box that encompass is the laser spot, rather than from thelaser spot only, has been a reliable technique for determining windmeasurements. Other portions of the image that do not include the laserspot are not utilized in obtaining wind measurements. It should be notedthat, although a “box” as described herein, embodiments mayalternatively use regions of other shapes.

FIG. 15 is a flow diagram of a method 1500 of determining the locationof a laser spot in an image, which can be implemented by a device suchas the laser-based optical device 100 of FIG. 1. As with other imagesprovided herein, FIG. 15 is a non-limiting example. Alternativeembodiments may vary from the functionality illustrated. It can be notedthat the blocks illustrated in FIG. 15 provide functionality similar toaspects of the functionality illustrated in the process 1200 of FIG. 12.As such, at least portions of the methods 1200 and 1500 may overlap.

At block 1510, the method includes obtaining, from a camera, a pluralityof images comprising a first set of images and a second set of images,wherein the first set of images comprises images of a scene taken over afirst period of time in which the laser spot is not present in thescene, and the second set of images comprises images of the scene takenover a second period of time in which the laser spot is present in thescene. As indicated earlier, the first set of images and the second setof images may be taken in sequence to help ensure that the first set ofimages and a second set of images are of substantially the same scene.

The functionality of blocks 1520 and 1530 comprises combining the imagesin the first set of images to create a first composite image andcombining the images in the second set of images to create a secondcomposite image, respectively. As noted previously, the composite imagefor a given image set may comprise pixels that have an average pixelvalue for corresponding pixels in each of the images of the given imageset. Pixel values for the composite image media can be determined inalternative ways according to some embodiments, such as a mean pixelvalue or weighted average.

At block 1540, a difference image is created by determining a differencein pixel values of pixels in the first composite image from pixel valuesof pixels in the second composite image. As noted above, this cancomprise subtracting pixel values of one composite image fromcorresponding pixel values from the other composite image.

At block 1550, a filtered difference image is created by applying aGaussian filter to the difference image. In the embodiments above, andSGF was used. Other embodiments may use other types of Gaussian filters.Moreover, techniques of applying that the Gaussian filter may vary. Insome embodiments, for example, the Gaussian filter may be applied row byrow. In some embodiments, the Gaussian filter may be applied column bycolumn.

At block 1560, one or more pixel values of one or more pixels of thefiltered difference image are compared with a threshold value todetermine the location of the laser spot within the filtered differenceimage. As noted with regard to FIG. 14B, this can provide for adetermination of the location of a Gaussian laser spot where noise andother features of the difference image have been filtered out.

Additional aspects may vary, depending on desired functionality. Forexample, some embodiments may further comprise finding a center locationof the laser spot, representative of the location of the laser spotwithin the filtered difference image. This center location may berepresented by (x, y) coordinates of a pixel value within the filtereddifference image. Some embodiments may further comprise defining abounding region within the filtered difference image (where the boundingregion comprises a region in which the laser spot is determined to belocated), and altering subsequent operation of the camera such that thecamera does not provide pixel data from pixel sensors corresponding topixels outside the bounding region for at least one subsequent imagecaptured by the camera. Additionally or alternatively, a size of thebounding region may be determined based on a determined the size of thelaser spot within the filtered difference image. In some embodiments forexample, a width of the bounding box (or radius of a circular boundingregion) may be a function of a determined width of the laser spot (e.g.,the width of the widest portion of the laser spot in terms of pixelswhose values exceed a threshold value). Finally, as noted in certainembodiments above, the camera may be configured to provide twostereoscopic images at a time (e.g., a right image and a left image,both captured simultaneously by the pixel sensor array of the camera).

Although embodiments of the laser-based optical device 100 have beendescribed as comprising the SWIR camera to provide for wind sensingmeasurements with an IR laser (e.g., at a wavelengths of 1550 nm or 904nm), wind measurements may be obtained in a similar manner using one ormore CMOS cameras to detect visible laser spots from visible-lightlasers. Such embodiments may utilize lasers that function at awavelength of approximately 600 nm, for example. Alternatively, as shownbelow, other sensors may be utilized instead of cameras.

Because the SWIR camera can be exceptionally expensive (a single cameracosting tens of thousands of dollars), alternatives to the laser-basedoptical device 100 may incorporate various lower-cost parts to helpreduce overall cost. Such a lower cost embodiments may further takeadvantage of equipment that users may already have. Such embodiments areprovided in further detail below.

Low-Cost Multifunction Wind and Range Measurement with BallisticComputer

FIG. 16 is a perspective view of an embodiment of a low-cost laser-basedoptical device 1600, with functionality similar to the laser-basedoptical device 100 of FIG. 2. (It is acknowledged that the term “lowcost” is relative. And indeed, the low-cost laser-based optical device1600 can be made at a relatively lower cost than the laser-based opticaldevice 100 of FIG. 2. Here, the term “low cost” is used to differentiatethe device illustrated in FIG. 16 from the device disclosed in earlierembodiments, and is not meant as a limitation on cost.) That is, thelow-cost laser-based optical device 1600 is capable of takinglaser-based range and wind measurements, along with providing other(non-laser-based) measurements. Size, weight, shape, and/or other traitscan vary, depending on desired features.

As shown in FIG. 16, embodiments of the low-cost laser-based opticaldevice 1600 can include optics 1610 through which a laser light istransmitted, and stereoscopic receiving optics 1620 through whichreflected laser light is received. The optics and/or other materialsused in the low-cost laser-based optical device 1600 can be similar tothose of the laser-based optical device 100 of FIG. 2.

FIG. 17 is a simplified block diagram illustrating various components ofa low-cost laser-based optical device 1600, according to one embodiment.Components can include, among other things, the central processing unit(CPU) 1710, a rangefinder codec 1715, the left optical sensor 1720, aright optical sensor 1725, a laser driver 1730, the user interface (UI)processor 1735, a compass 1740, a positioning unit 1745, and a tiltsensor 1750. Here, the low-cost laser-based optical device 1600 iscommunicatively coupled with an external ballistic computer 1760 via afirst communication interface 1765 and coupled to an external displayunit 1755 via a second communication interface 1770.

As with other figures provided herein, embodiments are not limited tothe components shown in figure. Variations may include combining wereseparating various components, adding or omitting components, and thelike. Depending on desired functionality, embodiments may include aninternal power source such as a battery, and/or utilize an externalpower source.

In the embodiment illustrated, the CPU 1710 is communicatively coupledto a controls many of the other components. Processing is furtherdivided between the CPU 1710 and other processors, including the UIprocessor 1735 and the rangefinder codec 1715. It can be noted, however,that processing may be further consolidated or distributed, depending ondesired functionality. In the embodiments below, the term “processingunit” may refer to the CPU 1710, the UI processor 1735, the rangefindercodec 1715, or any combination of the three (including all threecollectively).

Depending on desired functionality, the processing unit may comprise oneor more of an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), a general purpose processor, or thelike. The UI processor 1735 may be communicatively coupled with a userinterface (not shown), such as buttons, switches, a touchscreen, indoorother input/output devices, providing for communication between a userand low-cost laser-based optical device 1600. In some embodiments, theUI processor 1735 may be communicatively coupled with a wired orwireless interface, which can enable the low-cost laser-based opticaldevice 1600 to communicate with another device. (Such a wirelessinterface may comprise and/or be incorporated into the firstcommunication interface 1765 and/or the second communication interface1770. Alternatively wireless interface may be separate from these twocommunication interfaces.) For example, in some embodiments, the UIprocessor 1735, coupled with the wireless interface, may enable a userto configure the low-cost laser-based optical device 1600 using a mobiledevice (e.g., a smart phone) that communicates with the low-costlaser-based optical device 1600 wirelessly via the wireless interface.

This CPU 1710 is in communication with a laser driver 1730 to controlthe output of the laser for range finding and wind sensing measurements.Here, the laser driver 1730 comprises circuitry configured to operate alaser. In other embodiments, the laser driver 1730 may be incorporatedinto the laser itself (not shown) and/or the CPU 1710. The laser itselfcan comprise any of a variety of lasers with accompanying collimatingoptics to provide the desired wavelength, diffraction, and other opticaltraits to enable range finding and wind sensing measurements atoperating distances. One such laser may comprise a laser having aFabry-Perot seed laser and a pump laser combined with an optical fiberamplifier. Additional information regarding such a laser is provided inU.S. patent application Ser. No. 13/945,537, filed on Jul. 20, 2013,entitled “Compact Laser Source,” which is incorporated by referenceherein in its entirety.

The low-cost laser-based optical device 1600 may further comprisestereoscopic receiving optics, which can include a left optical sensor1720 and a right optical sensor 1725. The stereoscopic receiving opticscan be similar to those found in the laser-based optical device 100illustrated in FIG. 2 and described in the '004 application. Here,however, rather than utilizing the camera, such as the SWIR camera ofthe laser-based optical device 100, the left optical sensor 1720 and theright optical sensor 1725 may each comprise a photodiode, such as anavalanche photodiode or a PIN photodiode. Here, both the left opticalsensor 1720 and the right optical sensor 1725 provide output to the CPU1710 for wind measurement calculation.

For range finding measurements, only one of the optical sensors needs tobe utilized. In FIG. 17, the left optical sensor 1720 is shown to be incommunication with the rangefinder codec 1715. In other embodiments, itmay be the right optical sensor 1725. In some embodiments, both sensorsmay be in communication with the rangefinder codec 1715, and only oneused at a time to measure range.

As noted below, an optical sensor may need to have specialized circuitryin order to enable it to function for both wind sensing and rangefinding of functions. Such circuitry can be incorporated into the sensoritself, as described in more detail below.

For its part, the rangefinder codec 1715 coordinates with the CPU 1710to make range finding measurements. The CPU 1710 causes the laser driver1730 to generate laser pulses that enable range finding measurements tobe taken. The rangefinder codec 1715 then receives, via the left opticalsensor 1720, measurements of the laser light reflected off of thetarget. The rangefinder codec 1715 then uses an algorithm to determinethe range from the measurements. The range can then be provided to theCPU 1710.

The CPU 1710 may further gather additional sensor information from thetilt sensor 1750, positioning unit 1745, and the compass 1740. The tiltsensor 1750 can comprise, for example, a gyroscope capable ofdetermining a degree of tilt (e.g., with respect to gravity or theearth's surface) at which the low-cost laser-based optical device 1600is oriented. The tilt sensor 1750 may comprise alternative or additionalsensors capable of determining the tilt of the low-cost laser-basedoptical device 1600. The positioning unit 1745 can comprise a satellitepositioning receiver, for example, to determine an absolute or relativeposition of the low-cost laser-based optical device 1600 for ballisticcalculations. In some embodiments, the positioning unit 1745 comprisesand global positioning system (GPS) receiving unit capable ofdetermining an absolute position of the low-cost laser-based opticaldevice 1600 (e.g., coordinates in latitude and longitude). The compass1740 can comprise a magnetic, celestial, or other compass capable ofdetermining the orientation of the low-cost laser-based optical device1600 (e.g., in degrees) with respect to the geographic cardinaldirections.

Measurements from the tilt sensor 1750, positioning unit 1745, and acompass 1740, together with wind and range measurements taken of thetarget can be utilized to determine a ballistic solution for firing aweapon at the target. According to embodiments herein, this informationmay be provided to an external ballistic computer 1760 via the firstcommunication interface 1765 so that the external ballistic computer1760 can calculate the ballistic solution. Such embodiments can beadvantageous because many snipers in the field already utilize anexternal ballistic computer 1760. And thus, calculating a ballisticsolution internal to the low-cost laser-based optical device 1600 couldbe duplicative.

An external ballistic computer 1760 can receive the information providedby the low-cost laser-based optical device 1600 via the firstcommunication interface 1765 and utilize that information, together withother information, to calculate the ballistic solution. Such otherinformation can include, for example, temperature, humidity, and orother factors that could impact the ballistic solution. This can beadvantageous in situations where the low-cost laser-based optical device1600 may be in direct sunlight and/or the internal temperature and/orhumidity of the low-cost laser-based optical device 1600 is impacted bythe processing unit and/or and other components, in which case utilizingexternal sensors to measure the temperature and humidity may be moreaccurate. Nonetheless, according to some embodiments, temperature and/orhumidity sensors may be included in the low-cost laser-based opticaldevice 1600.

An external ballistic computer 1760 may include a temperature and/orhumidity sensors. Additionally or alternatively, the external ballisticcomputer 1760 may enable a user to input the temperature or humiditymanually via the user interface. External ballistic computers capable ofcalculating a ballistic solution are widely used in the field, andtherefore often readily available to users. They can enable users toinput a type of firearm and ammunition, utilizing that input, as well asdata from sensors and the low-cost laser-based optical device 1600 todetermine a ballistic solution. Examples of such external ballisticcomputers 1760 include ballistic solvers made by KESTREL and RAPTOR.

Depending on desired functionality, the external ballistic computer 1760may communicate with the first communication interface 1765 in any of avariety of ways. According to some embodiments, for example, thecommunication may be carried out wirelessly via Bluetooth and/or otherwireless radio frequency (RF) technologies. In some embodiments,wireless communication may be implemented via an IR interface. In someembodiments, communication may be implemented via wired communication,such as an RS252 serial port.

According to some embodiments, the external ballistic computer 1760 canthen compute the ballistic solution and provide the ballistic solutionback to the low-cost laser-based optical device 1600 via the firstcommunication interface 1765. According to some embodiments, theballistic solution comprises an offset aim point, which the low-costlaser-based optical device 1600 can then the aim point to an externaldisplay unit 1755 via the second communication interface 1770.Communication between the second communication interface 1770 and theexternal display unit 1755 can be wired and/or wireless, utilizing thewireless and/or wired technologies similar to those described withrespect to the communication between the first communication interface1765 and the external ballistic computer 1760.

In some embodiments the external display unit 1755 may be integratedinto and/or coupled with a weapon-mounted riflescope. In such instances,the offset aim point maybe displayed to a user looking through theriflescope, enabling the user to adjust his or her aim without takinghis or her eye off of the target to look at a separate display. (Thatsaid, the external display unit 1755, in some embodiments, can comprisea display that is visible to a spotter or that is not otherwise visiblethrough the riflescope.) One example of an external display unit 1755 isdescribed in in U.S. patent application Ser. No. 14/543,761, filed onNov. 19, 2014, entitled “Compact Riflescope Display Adapter” (referredto hereafter as “the '761 application”), which is incorporated byreference herein in its entirety.

FIGS. 18A and 18B are simplified drawings provided to help illustratehow an offset aim point may be displayed by an external display unit1755. It can be understood that, in the simplified drawings additionalinformation provided by the display is not shown. In some embodiments,for example, information such as range, humidity, temperature, and othersuch information may be displayed to a user, visible through theeyepiece of the riflescope.

FIG. 18A illustrates a view from the perspective of a user of theriflescope. Here, the eyepiece 1810 provides a magnified view of atarget 1820. The reticle 1830 allows the user to aim the weapon at thetarget 1820. According to embodiments herein, an offset aim point 1840is provided, indicative of a ballistic solution calculated by theexternal ballistic computer 1760. Here, because the offset aim point1840 is provided in the eyepiece 1810 of the riflescope via the externaldisplay unit 1755, the user does not have to view a separate display ortake his or her eye off the target in order to alter the aim of theweapon in accordance with the ballistic solution. Instead, as shown inFIG. 18B, the user simply needs to move the weapon on which theriflescope is mounted such that the offset aim point 1840 is now locatedon the target 1820.

FIG. 19 is a flow diagram, illustrating a method 1900 for acquiringdata, obtaining a ballistic solution, and providing ballistic solutionto an optical scope display, according to one embodiment. The method1900 can be implemented, for example, by a processing unit of thelow-cost laser-based optical device 1600. As with other figures herein,FIG. 19 is provided as an example. Other embodiments may vary infunctionality from the functionality shown. Variations may includeperforming additional functions, substituting functions, performingfunctions in a different order or simultaneously, and the like.

The functionality at block 1910 comprises causing the laser to emit alaser beam. The architecture shown in FIG. 17, for example, mayimplement this functionality where the CPU 1710 causes the laser driver1730 to operate the laser such that it emits a laser beam. In someembodiments, the functionality at block 1910 may be triggered by a userinput, such as pressing a button on the low-cost laser-based opticaldevice 1600. Alternatively, button, trigger, switch, or other inputdevice may trigger such functionality where the input device iscommunicatively the coupled with the low-cost laser-based optical device1600 and located on the weapon (e.g., at or near the trigger) for whichthe ballistic solution is intended to be calculated.

At block 1920, measurements of reflected light up the laser beam areobtained from the optical receiver. As explained previously, thesemeasurements may comprise optical measurements obtained from astereoscopic optical receiver, such as from the left optical sensor1720, and the right optical sensor 1725, shown in FIG. 17. Based onthese measurements, a crosswind between the low-cost laser-based opticaldevice 1600 and the target on which the laser light reflected can becalculated, at block 1930.

At block 1940, information indicative of the wind measurement is sentvia the first communication interface. As previously indicated, theinformation can be provided to an external ballistic computer. And itmay be provided via wireless or wired communication, according toproprietary or standardized communication protocols, depending ondesired functionality and relevant standards. In current embodiments,there are no relevant standards or protocols. Thus, proprietarycommunication techniques are utilized. However, industry standards inthe future may develop, and such standards and protocols can beimplemented in such cases.

At block 1950, a ballistic solution as received, subsequent to sendingthe information at block 1940. The ballistic solution can be provided bythe external ballistic computer via the first communication interface,for example. Again, communication technologies, protocols, and standardsmay vary, depending on desired functionality.

At block 1960, information is sent to an optical scope display via thesecond communication interface. As noted previously, the optical scopedisplay may be able to provide an offset aim point that is viewablethrough the eyepiece of the riflescope. As with the first communicationinterface, technologies, protocols, and/or standards may vary for thesecond communication interface may vary, depending on desiredfunctionality. Communication may be wired or wireless.

Some embodiments may provide additional functionality, if desired. Forexample, embodiments may comprise a positioning unit, where theprocessing unit is configured to obtain data from the positioning unit,and send the information obtained from the positioning unit via thecommunication interface. Similarly, embodiments may comprise one or moreorientation sensors, where the processing unit is further configured toobtain data from the one or more orientation sensors and send, via thefirst communication interface, information indicative of the dataobtained from the one or more orientation sensors. In some embodiments,the method may comprise causing cause the laser to emit one or morelaser pulses, obtaining one or more measurements of reflected light ofthe one or more laser pulses from one of the sensors of the opticalreceiver, calculating a range measurement based on the obtainedmeasurements of the reflected light, and sending, via the firstcommunication interface, information indicative of the rangemeasurement. In some embodiments, emitting the laser beam may be inresponse to receiving a request from the first communication interfaceand/or user input from the user interface

Embodiments of the low-cost laser-based optical device 1600 can gain anadditional cost advantage over traditional embodiments of thelaser-based optical device 100 by utilizing more cost effectivetechniques for bore sighting the laser. For example, traditionalembodiments of the laser-based optical device 100 may includeelectrically controlled Risley prisms at the output of the laser,enabling the device to steer the laser for manual or automatic boresighting. Embodiments of the low-cost laser-based optical device 1600,on the other hand, may utilize a manual mount capable of maintainingbore sight after receiving the shock of firing a weapon (which can be1000 g or more). Embodiments of such a mount are provided below.

Stabilized Weapon Mount

FIG. 20 is an embodiment of a stabilized weapon mount 2000 for thelow-cost laser-based optical device 1600 and/or other weapon-mounteddevices. Current manual mounts typically utilize friction or springjoints that fail to allow for movement of a relatively large massstructure (e.g., the optical scope or other mounted device) withprecision while at the same time prohibiting any “creep” or drift thestructure's initial alignment that induced shock from gun fire maycause. This is further complicated by the need for both elevation andazimuth degrees of freedom, which may undermine the rigidity of theother.

Embodiments provided herein, such as stabilized weapon mount 2000 ofFIG. 20, isolate these axes from each other and provide a means tosecurely lock the joints to prevent movement. The payload of the mountmay be a laser pointing system (such as the low-cost laser-based opticaldevice 1600) that can be finely adjusted to less than a few hundredmicroradians relative to a riflescope aim point. Without isolation,adjusting either axis may induce length change to the payload mountingbeam. Typical systems tolerate that change in the adjustment threadengagement play, but result in too little torque friction that causesbore sighting drift problems after gun shots. As a result, the presentindustry approaches fail to maintain bore sight after gun shots,particularly less than one milliradian.

Embodiments of the present invention address these and other issues byproviding a mounting system with low viscous friction duringazimuth/elevation adjustment, axes isolation so that the adjusters donot require large thread engagement play, isolation for the lengthchanges of the payload beam for the cos theta changes for eitherelevation and azimuth, and a bi-directional locking feature so that theadjusters themselves and the payload beam are torqued from both ends tocounteract the induced shock loads. Put differently, embodiments of theinvention allow the mounting system to accept a payload and provideindependent bore sighting adjustment capability for precision azimuthand elevation changes, while securely locking the mechanism to achieveminimal bore sighting drift after repeated gun shocks. It can be noted,however, that the embodiments of the mounting system herein can beutilized in applications other than weapon-mounted configurations.

Referring again to FIG. 20, the stabilized weapon mount 2000, accordingto this embodiment, can comprise the following components: an azimuthlocking screw 2005, azimuth block 2010, front support arms 2015, azimuthadjustment screw 2020, front azimuth flexure 2025, vertical supportblock 2030, front elevation flexure 2035, vertical support flexure 2040,payload block 2045, base block 2050, rear elevation flexure 2055, pivotblock 2060, rear azimuth flexure 2065, vertical adjustment block 2070,rear supporting arm 2075, elevation adjustment screw 2080, and elevationlocking screws 2085. It can be understood that embodiments may vary fromthat which is shown. In accordance with some embodiments, for example,the payload block 2045 may be incorporated into the frame or body of anoptical scope or other payload. In such instances, therefore, thestabilized weapon mount 2000 may be built into a payload.

Depending on desired functionality and manufacturing concerns,components described herein may be comprised of any of a variety ofmaterials. According to some embodiments aluminum and/or steel may beutilized. Ultimately, the materials utilized can be chosen to becompliant enough to rely out the movement described herein withoutbreaking. A person of ordinary skill in the art would understand howthese materials may be chosen.

Operation of the stabilized weapon mount 2000 can proceed generally asfollows. The azimuth adjustment screw 2020 can be adjusted to controlthe distance between the azimuth block 2010 and the front support arms2015, thereby controlling the lateral rotation of the payload block 2045by acting through the front azimuth flexure 2025, the vertical supportblock 2030 and the front elevation flexure 2035. To enable thisfunctionality, the front support arms 2015 can be threaded, enablingboth the azimuth adjustment screw 2020 and the azimuth locking screw2005 to move inward and outward, relative to the front support arm 2015.In some embodiments, the front support arm 2015 that is treaded for theazimuth adjustment screw 2020 need not have the same thread as theazimuth locking screw 2005 or azimuth block 2010. Depending on desiredfunctionality, manufacturing concerns, and/or other factors, the azimuthblock 2010 may be driven by a differential screw (as shown) or a directacting screw. In some embodiments, the front support arms 2015 may be abolted or otherwise fastened to the base block 2050. Alternatively, thefront support arms 2015 may be an integral part thereof.

The azimuth block 2010 can be threaded to pass the azimuth adjustmentscrew 2020. The azimuth block also mounts front azimuth flexure 2025,which (along with front elevation flexure 2035) allows lateral rotationbetween the azimuth block 2010 and the vertical support block 2030. Itcan be noted that the azimuth block 2010 does not pivot as ittranslates. The azimuth adjustment screw 2020 determines the lateralposition of the azimuth block 2010. The vertical, axial and rotationalpositions of azimuth block 2010 are not determined by the azimuthadjustment screw.

Once the azimuth block 2010 is in place (via adjustment of the azimuthadjustment screw 2020), the azimuth locking screw 2005 is then used tosecure the azimuth block 2010 into place. The azimuth locking screw 2005threads through one of the front support arms 2015. In some embodiments,the azimuth locking screw 2005 can slide over azimuth adjustment screw2020 and push against the azimuth block 2010. This secures the azimuthadjustment from drift. It also removes any residual tolerances in theazimuth adjustment.

FIG. 21 is a simplified diagram of a cross-section of the azimuth block2010, azimuth locking screw 2005, front support arms 2015 and azimuthadjustment screw 2020, according to one embodiment. In this embodiment,the azimuth adjustment screw 2020 is fixed relative to the front supportarms, thereby causing the azimuth block 2010 to move relative to thefront support arms 2015 when the azimuth adjustment screw 2020 isadjusted. Azimuth locking screw 2005 can slide over azimuth adjustmentscrew 2020 and push against the azimuth block 2010 to ensure minimalmovement.

When the azimuth block 2010 is moved by means of the azimuth adjustmentscrew 2020, the front azimuth flexure 2025, together with the rearazimuth flexure 2065, enable lateral rotation of the components betweenthem, including the vertical support block 2030, the payload block 2045(along with the payload mounted thereon), and the pivot block 2060.Depending on desired functionality, the flexures shown herein (2025,2035, 2055, and 2065) may be a unitary assembly or may be discreteparts. They may be bonded, welded, or otherwise fastened to theirrespective mounting blocks.

Similarly, when the vertical adjustment block 2070 is moved by means ofthe elevation adjustment screw 2080, as described below, the frontelevation flexure 2035, together with the rear elevation flexure 2055,enable vertical rotation of the vertical support block 2030, the payloadblock 2045, and the pivot block 2060.

The vertical support block 2030 sits on the front of the front elevationflexure 2035. According to some embodiments, the vertical support block2030 may be fixed in height above the base block 2050. The axialposition of the vertical support block 2030 may be fixed by the frontelevation flexure 2035. According to some embodiments, a single frontelevation flexure may rest under the vertical support block 2030. Analternative configuration allows for two front elevation flexures underthe azimuth block 2010.

As mentioned previously the payload block 2045 may be rotated; itselevation and azimuth angles are adjustable via adjustment screws (2020,2080). Depending on desired functionality, the payload block 2045 may bea unitary assembly or composed of discrete parts. The parts may bebonded, welded or fastened together. The payload block 2045 is the partto which the payload may be permanently or removably mounted.

The base block 2050 can be fixed in a static position or positioned byother external means. In some embodiments, it may be mountable to aPicatinny rail. As with other components described herein, the baseblock 2050 may be a unitary assembly or comprised of discrete parts thatmay be fastened together to form a rigid structure.

As noted previously, the rear elevation flexure 2055 allows the payloadblock to change elevation angle. The rear elevation flexure 2055 alsorestrains the elevation and lateral position of the rear of the payloadblock and restrains the roll rotation of the payload block.

The pivot block 2060 connects the rear elevation flexure 2055 and therear azimuth flexure 2065. The pivot block 2060 determines the positionof the rear of the payload block 2045 while allowing the payload block2045 to move in elevation and azimuth. It also controls the rollrotation of the payload block 2045. The pivot block 2060 may be aunitary assembly or composed of discrete parts fastened together to forma rigid structure.

The rear azimuth flexure 2065 allow lateral rotation between the pivotblock 2060 and the vertical adjustment block 2070. The rear azimuthflexure 2065 defines the lateral position of the pivot block 2060 andthe roll angle of the pivot block 2060.

The vertical adjustment block 2070 defines the vertical separationbetween the base block 2050 and the rear of the payload block 2045. Thevertical adjustment block 2070 is threaded to pass the elevationadjustment screw 2080. The vertical adjustment block 2070 is controlledin elevation by the elevation adjustment screw 2080 and constrained inits lateral and axial position and its angle of pitch and roll by therear elevation flexure 2055. According to embodiments, the verticaladjustment block 2070 does not pivot as it translates vertically. Theelevation adjustment screw 2080 determines the vertical position of thevertical adjustment block 2070. According to some embodiments, thethreaded aperture for the elevation adjustment screw can be both slottedand threaded. It also has a clearance and threaded hole for theelevation locking screw.

FIG. 22 is a simplified diagram of a cross-section of the elevationadjustment screw 2080, the vertical adjustment block 2070, and elevationlocking screws 2085, according to one embodiment. In this embodiment,the elevation adjustment screw 2080 is fixed relative to the base block2050, causing the vertical adjustment block 2070 to move relative to thebase block 2050 when the elevation adjustment screw 2080 is adjusted.Elevation locking screws 2085 press against unthreaded portions of theelevation adjustment screw 2080 to ensure minimal movement.

The elevation adjustment screw 2080 controls the separation between thevertical adjustment block 2070 and the base block 2050. The elevationadjustment screw 2080 controls the vertical rotation of the back of thepayload block by acting through the rear azimuth flexure 2065, the pivotblock 2060, and the rear elevation flexure 2055. The elevationadjustment screw may be a differential screw (as shown) or a directacting screw.

The elevation locking screws 2085 are mounted in the vertical adjustmentblock 2070 and the base block 2050. The elevation locking screws 2085control the thread clearance around the elevation adjustment screw 2080.The elevation locking screws 2085 stop rotation of the elevationadjustment screw 2080 and also eliminate the axial play along theelevation adjustment screw 2080 by closing the thread clearance.

It can be noted that the embodiments described above are provided as anexample only. Other embodiments may vary on this basic structure.Additionally, although the terms “front” and “back” are used, designedit used simply as a matter of convention. In practice, the stabilizedweapon mount 2000 may be rotated 180°. That is, embodiments may utilizesuch that there is no “front” or “back.” Additionally, alternativeembodiments may utilize different thread configurations for the screws,position one or more screws at a different location, or provide othersuch variations, depending on desired functionality.

Optical Sensor for Range Finding and Wind Sensing Measurements

Returning again to FIG. 17, embodiments of the low-cost laser-basedoptical device 1600, may include left and right optical sensors 1720 and1725, respectively. And as previously indicated, such sensors cancomprise a photodiode. It can be noted, however, that additionalcircuitry may be needed in order to provide adequate measurements forboth range finding and wind sensing. Moreover, it may be undesirable toattempt to incorporate such circuitry into the CPU 1710 or rangefindercodec 1715 due to the additional capacitance that routing lines wouldcreate, which can be detrimental to functionality of the optical sensors1720, 1725.

Below, techniques are disclosed for providing an optical sensor that canbe used for wind sensing in an optical scope. The optical sensor caninclude a photodiode, an electrical switch, a trans-impedance amplifier(TIA), and a capacitive trans-impedance amplifier (CTIA), enabling theoptical sensor to perform both wind-sensing and range-finding functions.Some embodiments may include some or all of these components in anapplication-specific integrated circuit (ASIC), depending on desiredfunctionality. In keeping the TIA, CTIA, and other circuitry close tothe photodiode, this reduces the capacitance of routing lines connectingthe circuitry to the photodiode, thereby reducing the impact of suchrouting lines in the functioning of the sensor.

FIG. 23 is a circuit diagram of an integrated sensor 2300, according toone embodiment. As shown, inputs of the integrated sensor 2300 comprisea detector bias, VDC, return (RTN) (e.g., ground), switch (SW), and anintegration reset input. Outputs include signals for laser range finding(LRF) and wind sensing (“Wind”). As can be seen, the integrated sensor2300 includes a switch that is activated with the SW input. The switchenables the integrated sensor 2300 to toggle between circuitry, enablingthe integrated sensor 2300 to perform laser range finding functions orwind sensing functions, depending on which function is needed.

The switch is coupled to the output of diode D1, connecting D1 witheither the trans-impedance amplifier (TIA) or a capacitivetrans-impedance amplifier (CTIA), as needed.

The TIA is utilized when taking laser range finding measurements. Whenoperating in a laser range finding mode, the integrated sensor 2300operates with the switch connecting the output of diode D1 to the inputof the TIA. The TIA operates as a low pass filter that integrates anincoming signal but decays over time. According to some embodiments, theTIA is capable of receiving a plurality of pulses from diode D1, as aresult of pulsed laser light being transmitted by a laser transmitterand reflected off of the target. The bandwidth of the TIA may varydepending on desired functionality. According to some embodiments, thisbandwidth can be approximately 50 MHz. The optical pulse is received atD1 can vary in width, depending on desired functionality. According tosome embodiments, for example, optical pulse is can be between 10 and 22ns, and each pulse will be integrated by the TIA.

The TIA can enable the integrated sensor 2300 to provide standardrange-finding functionality. According to some embodiments, for example,approximately 100,000 pulses of laser light may be received over aperiod of 100 ms. These pulses can be added up into a “range gate” toreduce the effect of noise (where the signal increases linearly, but thenoise sums as a square root). The LRF signal of the integrated sensor2300 can be provided to an analog to digital converter (ADC) for rangefinding calculations.

The CTIA is utilized when taking wind sensing measurements. Whenoperating in a wind sensing mode, the integrated sensor 2300 operateswith the switch connecting the output of diode D1 to the input of theCTIA. In contrast to the TIA, the CTIA does not decay over time,although it can be reset with the integration reset input signal.

During wind sensing measurements, the laser transmitter emits acontinuous wave (CW) laser beam, according to some embodiments. Here,the laser light may be only slightly above background noise. (To helpenable wind sensing measurements, powerful fiber laser can be used withlow beam divergence. Sun filters and/or other optics can be used to helpreduce the background noise and corresponding noise current at theCTIA.) During operation, the output of the diode D1, resulting fromnoise and received laser light, is provided to the CTIA, whichintegrates this signal over time. Depending on desired functionality,the refresh rate of the output can vary. According to some embodiments,the CTIA integrates over a period of 1 ms. The output of the CTIA isthen read, and the CTIA is reset via the integration reset input of theintegrated sensor 2300. This process is conducted over and over toobtain different readouts and determine scintillations in the received alaser light. The output can then be provided to a processor or othercircuitry to analyze the outputs and determine a crosswind measurementas discussed previously.

According to some embodiments, noise may be reduced using additional oralternative techniques. For example, the CTIA may integrate over aperiod of time during which the laser transmitter is not transmitting alaser beam. This can be done in order to determine a baseline noiselevel. Then the CTIA can integrate over an equal period of time with thelaser light. The two signals—with and without the laser light—can thenbe subtracted, thereby canceling out noise common between the twosignals.

The type of diode D1 can vary, depending on desired functionality.According to some embodiments, for example, the diode can comprise a PINdiode. In some embodiments, this may be an InGaS mesa PIN diode. In someembodiments, the diode may comprise a flip-chip diode.

According to some embodiments, the circuitry in FIG. 23 accompanying thediode can be disposed in an ASIC. Additionally, the diode and thecircuitry may be disposed in a single package, as shown in FIGS. 24A and24B.

FIGS. 24A and 24B are, respectively, simplified cross-sectional andperspective illustrations of an example package 2400 into which theintegrated sensor 2300 may be incorporated. Here, the photodetector 2410(e.g., diode D1 of FIG. 23) is situated near a window 2430, providingthe photodetector 2410 with a field of view 2420 sufficient to providefor the functionality described herein above. According to someembodiments, the photodetector 2410 may be disposed on a pedestal 2415mounted on the circuit card 2450 to help ensure the proper spacing ofthe photodetector 2410 from the window 2430. ASIC 2440 can be disposednearby on the circuit card 2450. As noted above, the utilization of anASIC 2440 (rather than discrete components), along with its proximity tothe photodetector 2410 can help keep lead length low, reducing possibledegradation due to stray capacitance caused by the leads. The package2400 can be hermetically sealed, according to embodiments, and pins 2460can be utilized to incorporate the package 2400 onto a larger circuitboard, connecting the components within the package 2400 with othercomponents of a low-cost laser-based optical device 1600, for example.The package 2400 may further include other circuitry 2470 (e.g., inaddition to the ASIC 2440) for noise canceling and/or filtering.

FIG. 25 is a circuit diagram illustrating how integrated sensors 2300-1and 2300-2 can be utilized for laser range finding and wind sensing in alarger device (e.g., the low-cost laser-based optical device 1600 ofFIG. 17), in one embodiment. Here, the right sensor 2300-1 is utilizedfor both wind sensing and range finding measurements. The left sensor2300-2 is utilized only for wind sensing. As can be seen, the LRF outputof the integrated sensor 2300-2 is not connected with a processing unit.As with other figures herein, embodiments are not limited to theconfiguration shown in FIG. 25. Additionally, it will be understood thatvarious components are omitted for clarity. For example, the SW input ofone or both of the integrated sensors 2300 may be provided by aprocessing unit that is not shown. Moreover, the output measurementslabeled “Range” and “Crosswind speed & Direction” can be provided to aprocessing unit that is not shown. Components labeled as FPGAs may bereplaced with other types of processing units, ASICs, or other IPequaling circuitry.

It can be noted that one or more components shown in FIG. 25 maycorrelate with components of the low-cost laser-based optical device1600, as shown in FIG. 17. For example, integrated sensors 2300-1 and2300-2 can correlate with right optical sensor 1725 and left opticalsensor 1720, respectively. The Rangefinder CODEC (FPGA) of FIG. 25 cancorrelate with the rangefinder codec 1715 of FIG. 17. A person ofordinary skill in the art will recognize additional correlations.

The functionality of the components shown in FIG. 25 can be generallydescribed as follows. The transmit laser may generate pulses for laserrange finding as a result of input from the Rangefinder CODEC (FPGA).Reflected laser light can then enter the right side receive aperture andthe left side receive aperture, detected by the photodetectors of theright integrated sensor 2300-1 and the left integrated sensor 2300-2,respectively. During the range finding mode, the switch can connect thephotodetectors of each integrated sensor to the corresponding TIAcircuitry. Because the TIA circuitry of the left integrated sensor2300-2 is not connected with an output, signals output by the TIA areignored. However, the output of the TIA circuitry of the rightintegrated sensor 2300-1 is provided to an ADC, which converts theoutput of the TIA to a digital signal and provides it to the RangefinderCODEC (FPGA). The Rangefinder CODEC (FPGA) then calculates the rangebased on the input from the ADC and provides the range measurement as anoutput.

When operating in a wind sensing mode, the transmit laser can generate alaser beam that illuminates a target. Reflected laser light enters theright side received aperture and the left side receive aperture,illuminating the photodetectors in the right integrated sensor 2300-1and the left integrated sensor 2300-2, respectively. In the wind sensingmode, the switch connects the output of the photodetectors of eachintegrated sensor 2300 to corresponding CTIA circuitry. The outputs ofthe CTIA circuitry of both integrated sensors 2300 are provided torespective ADC circuits, which convert the analog input from the CTIAcircuitry to a digital signal. This is then provided to the Wind (FPGA).The Wind (FPGA) uses these input digital signals to calculate crosswindspeed and direction, which it then provides as an output.

As previously noted, the integrated sensors 2300 can be incorporated itinto devices such as the low-cost laser-based optical device 1600 ofFIG. 17. However, other devices may also take advantage of such sensors.This can include a more fully-integrated device, as described below.

Riflescope with Integrated Wind Sensor and Targeting Display

Embodiments of optical devices described previously provide for windsensing and range-finding measurements, and may communicate withadditional devices such as a riflescope and the riflescope display,among other things. However, additional devices are contemplated. Onesuch device is illustrated in FIG. 26.

FIG. 26 is a perspective view of an integrated riflescope 2600,according to some embodiments. The integrated riflescope 2600 comprisesa weapon-mounted optical scope that determines crosswind measurementsand displays a ballistic solution without the need for a separatedevice. As such, the integrated riflescope 2600 can provide anall-in-one solution for weapon-mounted sniper and other applications.

As with other embodiments herein, the integrated riflescope 2600 cancomprise laser transmitter optics 2610 and stereoscopic laser receiveroptics 2620, capable of transmitting and receiving a laser beam andcalculating wind measurements therefrom. According to the embodimentillustrated, a second laser transmitter optics 2630 may be included. Thesecond laser transmitter optics 2630 can comprise a laser distinct fromthe laser of the laser transmitter optics 2610 for range-finding. Thus,according to the embodiment illustrated, a first laser may utilize lasertransmitter optics 2610 to emit a laser beam for wind sensingmeasurements. The second laser transmitter optics 2630 may be utilizedby a second laser to transmit laser pulses for range-findingmeasurements. It can be noted, however, that other embodiments mayincorporate these two laser transmitter optics, using a single lasertransmitter for both wind sensing and range-finding applications.

Embodiments of the integrated riflescope 2600 may further include adisplay 2640 at the input aperture (rather than internally at thefirst-focal-plane, enabling for simpler, more cost-effectiveembodiments). Details regarding a display 2640 capable of beingincorporated into a device at the input aperture are provided in the'761 application, which was previously incorporated herein above.Because the display 2640 is incorporated into the integrated riflescope2600, it may share common housing components and/or may include internalwiring connecting the electronic components of the integrated riflescope(including components used for range-finding and/or wind sensing) withthe display 2640.

The integrated riflescope 2600 can be advantageous in several respects.The placement of the laser transmitter optics 2610, 2630 in thestereoscopic laser receiver optics 2620 above the body of the riflescope2660 can help ensure that range-finding and wind sensing functions arenot hindered by additional elements in front of the integratedriflescope 2600, such as an IR camera. Because the display 2640 and windsensing and range-finding components can be securely fastened togetherin a single housing, problems with regard to misalignment between thecomponents are minimized.

Other features of the integrated riflescope 2600 include, and eyepiece2650 and turret adjustments 2670. The turret adjustments 2670 canprovide pan, tilt, and rotation for alignment of the integratedriflescope 2600 with the weapon on which it is mounted. A user may viewthe target via the eyepiece 2650, which may provide a magnified view ofthe target, as well as possible information displayed by the display2640. Such information can include, for example, offset aim point (asdetermined by a ballistic computer from, for example, range and/or windmeasurements obtained from these functions of the integrated riflescope2600), range, wind measurement, temperature, humidity, bearing, andother such information gathered from sensors within the device and/orinformation provided to the device by, for example, a separate device.

Electrical components of the integrated riflescope 2600 can be similarto the components of the low-cost laser-based optical device 1600 ofFIG. 17, as described previously. The integrated riflescope 2600 mayfurther include additional sensors, such as humidity, temperature,and/or the like, which it may use for computing a ballistic solution.Additionally, embodiments may provide for an external ballistic computerto be utilized in the manner described above with regard to the low-costlaser-based optical device 1600. Alternatively, the integratedriflescope 2600 may compute a ballistic solution internally using aprocessing unit (such as the CPU 1710 of FIG. 17).

As with the low-cost laser-based optical device 1600, the integratedriflescope 2600 may comprise one or more communication interfaces. Theseinterfaces may communicate with other devices using wireless or wiredtechnology, as described above with regard to the low-cost laser-basedoptical device 1600.

FIG. 27 is a perspective view of an integrated riflescope 2700,according to another embodiment. As can be seen, the integratedriflescope 2700 of FIG. 27 is similar in many respects to the integratedriflescope 2600 of FIG. 26, such as providing a display at the inputaperture, providing a laser transmitter and stereoscopic receivingoptics for wind sensing applications, and providing separate transmitteroptics for range finding applications. The integrated riflescope 2700further includes turret adjustments that can adjust the alignment of theintegrated riflescope 2700 in the manner described previously withregard to the integrated riflescope 2600. The integrated riflescope 2700of FIG. 27, however, includes additional features, as illustrated.

One such additional feature is a keypad 2710. According to someembodiments, the keypad 2710 can be used for initial alignment andconfiguration. That is, it can be utilized as an input to one or more ofthe electrical components disposed within the integrated riflescope2700. The type, configuration, and amount of buttons or other inputelements of the keypad 2710 may vary, depending on desiredfunctionality.

Another additional feature is an enhanced image assembly 2720. As shown,according to some embodiments, the enhanced image assembly 2720 can bedisposed in the integrated riflescope 2700 near the eyepiece. Theenhanced image assembly 2720 can provide a user looking through theeyepiece of the integrated riflescope 2700 with an enhanced image of thetarget at which the integrated riflescope 2700 is aimed. The enhancedimage assembly 2720 can do this by capturing a portion of the lightentering the aperture of the integrated riflescope 2700, performingimage processing on the captured light to create an enhanced image, andproviding the enhanced image on a display viewable through the eyepieceof the integrated riflescope 2700. The enhanced image assembly 2720 mayinclude a dial 2730 (or other mechanism) that enables a user to switchbetween direct view and enhanced view modes.

For example, the dial 2730 may cause a mirror to toggle between directview and enhanced view modes. In the direct view mode, the mirror is outof the pathway of light entering the aperture in passing through theintegrated riflescope 2700 to the eyepiece. In the enhanced view mode,the mirror is configured to direct light from a display such that it isvisible through the eyepiece. This functionality is illustrated in FIGS.28A and 28B.

FIG. 28A is a simplified cross-sectional view of the integratedriflescope 2700 of FIG. 27, according to one embodiment. It can be notedhowever, that additional optical elements may be present in alternativeembodiments to provide for magnification and/or other functionality.

Here, the integrated riflescope 2700 is operating in a direct view mode.In this mode, light 2840 entering that aperture passes through theoptics of the integrated riflescope to the eyepiece 2830, allowing auser looking into the eyepiece 2830 to view a target at which theintegrated riflescope 2700 is aimed. The dial 2730 (not shown here) isadjusted such that a mirror 2820 is not in the optical path of the light2840. A beam splitter 2870 may be tuned to deflect only near IR and/orIR light, thereby allowing visible light to pass through to theeyepiece. In the direct view mode, display optics 2810 may causeadditional light 2860 to enter through the aperture for display to auser. As indicated previously, the display may provide an offset aimpoint, temperature, humidity, and/or other readings or measurements,depending on desired functionality. This information is viewable to auser through the eyepiece 2830, and overlaid on the incoming image.

FIG. 28B is a simplified cross-sectional view of the integratedriflescope 2700 operating in an enhanced view mode. Here, the dial 2730is adjusted such that the mirror 2820 obstructs the visible lightpassing through the integrated riflescope and directs light coming fromthe enhanced image display 2880 the eyepiece 2830. The beam splitter2870 redirects a portion of the light (such as near IR and/or IR light)to CMOS camera 2890. (Other optical elements such as mirrors or lensesmay be utilized, as shown.) The image captured at the CMOS camera 2890is then processed to undergo various image enhancements, and the outputimages are displayed on an enhanced image display 2880. As shown,various optics including the mirror 2820 to direct light from theenhanced image display 2880 to the eyepiece 2830 such that the image onthe enhanced image display 2880 is viewable to a user looking into theeyepiece 2830.

The enhanced image display 2880 can utilize any of a variety oftechnologies, depending on desired functionality. For example, theenhanced image display 2880 may be a liquid crystal display (LCD), alight emitting diode (LED) display, an organic LED (OLED) display, andthe like. Aspects of the display such as brightness, contrast, and thelike may be adjustable by a user, according to some embodiments.

The processing of the images can vary, depending on desiredfunctionality. Frequently, the turbulence that enables wind sensingmeasurements to be taken between a target and the integrated riflescope2700, can cause blur in an image of the target. In some embodiments,therefore, the image captured by the CMOS camera 2890 can be provided toa processing unit for image processing. Such image processing caninclude image sharpening and/or other techniques for reducing blur orproviding other enhancements. Depending on the processing power of theprocessing unit, the enhanced images can be output on the enhanced imagedisplay 2880 at a speed of approximately 10 to 15 fps. According to someembodiments, the processing unit may comprise a CPU (e.g., the CPU 1710of FIG. 17). In other embodiments, the processing unit may comprise aspecialized processing unit, such as a digital image processor, digitalsignal processor, and/or the like.

As illustrated, the display optics 2810 may not provide input at theaperture of the integrated riflescope 2700 when the integratedriflescope 2700 is operating in an enhanced view mode. This is becauseinformation that would normally be overlaid on the incoming image by thedisplay optics 2810 can instead be provided in the image shown on theenhanced image display 2880. (E.g., the processing unit generating theenhanced image can cause text and/or other object to be shown in theenhanced image.) That said, embodiments may provide for the utilizationof the display optics 2810 during an enhanced view mode, pending ondesired functionality.

Various components may be described herein as being “configured” toperform various operations. Those skilled in the art will recognizethat, depending on implementation, such configuration can beaccomplished through design, setup, placement, interconnection, and/orprogramming of the particular components and that, again depending onimplementation, a configured component might or might not bereconfigurable for a different operation.

Computer programs incorporating various features of the presentinvention may be encoded on various computer readable storage media;suitable media include magnetic media, optical media, flash memory, andthe like. Non-transitory computer-readable storage media encoded withthe program code may be packaged with a compatible device or providedseparately from other devices. In addition program code may be encodedand transmitted via wired optical, and/or wireless networks conformingto a variety of protocols, including the Internet, thereby allowingdistribution, e.g., via Internet download.

While the principles of the disclosure have been described above inconnection with specific embodiments, it is to be clearly understoodthat this description is made only by way of example and not aslimitation on the scope of the disclosure. Additional implementationsand embodiments are contemplated. For example, the techniques describedherein can be applied to various forms of optical devices, which maycomprise a smaller portion of a larger optical system. Yet furtherimplementations can fall under the spirit and scope of this disclosure.

What is claimed is:
 1. A method of determining a location of a laser spot in an image, the method comprising: obtaining, from a camera, a plurality of images comprising a first set of images and a second set of images, wherein: the first set of images comprises images of a scene taken over a first period of time in which the laser spot is not present in the scene, and the second set of images comprises images of the scene taken over a second period of time in which the laser spot is present in the scene; combining the images in the first set of images to create a first composite image; combining the images in the second set of images to create a second composite image; creating a difference image by determining a difference in pixel values of pixels in the first composite image from pixel values of pixels in the second composite image; creating a filtered difference image by applying a Gaussian filter to the difference image; and comparing one or more pixel values of one or more pixels of the filtered difference image with a threshold value to determine the location of the laser spot within the filtered difference image.
 2. The method of determining the location of a laser spot within an image of claim 1, further comprising finding a center location of the laser spot, representative of the location of the laser spot within the filtered difference image.
 3. The method of determining the location of a laser spot within an image of claim 1, further comprising: defining a bounding region within the filtered difference image, the bounding region comprising a region in which the laser spot is determined to be located; and altering subsequent operation of the camera such that the camera does not provide pixel data from pixel sensors corresponding to pixels outside the bounding region for at least one subsequent image captured by the camera.
 4. The method of determining the location of a laser spot within an image of claim 3, further comprising determining a size of the bounding region, based on a determined the size of the laser spot within the filtered difference image.
 5. The method of determining the location of a laser spot within an image of claim 1, wherein the camera is configured to provide two stereoscopic images at a time.
 6. A laser-based optical device comprising: a camera configured to capture a plurality of images comprising a first set of images and a second set of images, wherein: the first set of images comprises images of a scene taken over a first period of time in which a laser spot is not present in the scene, and the second set of images comprises images of the scene taken over a second period of time in which the laser spot is present in the scene; a processing unit communicatively coupled with the camera and configured to: obtain, from the camera, the plurality of images; combine the images in the first set of images to create a first composite image; combine the images in the second set of images to create a second composite image; create a difference image by determining a difference in pixel values of pixels in the first composite image from pixel values of pixels in the second composite image; create a filtered difference image by applying a Gaussian filter to the difference image; and compare one or more pixel values of one or more pixels of the filtered difference image with a threshold value to determine a location of the laser spot within the filtered difference image.
 7. The laser-based optical device of claim 6, wherein the processing unit is further configured to find a center location of the laser spot, representative of the location of the laser spot within the filtered difference image.
 8. The laser-based optical device of claim 6, wherein the processing unit is further configured to: define a bounding region within the filtered difference image, the bounding region comprising a region in which the laser spot is determined to be located; and alter subsequent operation of the camera such that the camera does not provide pixel data from pixel sensors corresponding to pixels outside the bounding region for at least one subsequent image captured by the camera.
 9. The laser-based optical device of claim 8, wherein the processing unit is further configured to determine a size of the bounding region, based on a determined the size of the laser spot within the filtered difference image.
 10. The laser-based optical device of claim 6, wherein the camera is configured to provide two stereoscopic images at a time.
 11. The laser-based optical device of claim 10, further comprising a stereoscopic optical receiver configured to focus light on two portions of the camera, resulting in the two stereoscopic images.
 12. The laser-based optical device of claim 6, further comprising a laser, wherein the processing unit is further configured to cause the laser to emit a laser beam that generates the laser spot.
 13. The laser-based optical device of claim 6, wherein the camera is a shortwave infrared (SWIR) camera.
 14. A non-transitory computer readable medium having instructions embedded thereon for determining a location of a laser spot in an image, the instructions including computer code for: obtaining, from a camera, a plurality of images comprising a first set of images and a second set of images, wherein: the first set of images comprises images of a scene taken over a first period of time in which the laser spot is not present in the scene, and the second set of images comprises images of the scene taken over a second period of time in which the laser spot is present in the scene; combining the images in the first set of images to create a first composite image; combining the images in the second set of images to create a second composite image; creating a difference image by determining a difference in pixel values of pixels in the first composite image from pixel values of pixels in the second composite image; creating a filtered difference image by applying a Gaussian filter to the difference image; and comparing one or more pixel values of one or more pixels of the filtered difference image with a threshold value to determine the location of the laser spot within the filtered difference image.
 15. The non-transitory computer readable medium of claim 14, wherein the instructions further comprise computer code for finding a center location of the laser spot, representative of the location of the laser spot within the filtered difference image.
 16. The non-transitory computer readable medium of claim 14, wherein the instructions further comprise computer code for: defining a bounding region within the filtered difference image, the bounding region comprising a region in which the laser spot is determined to be located; and altering subsequent operation of the camera such that the camera does not provide pixel data from pixel sensors corresponding to pixels outside the bounding region for at least one subsequent image captured by the camera.
 17. The non-transitory computer readable medium of claim 16, wherein the instructions further comprise computer code for determining a size of the bounding region, based on a determined the size of the laser spot within the filtered difference image.
 18. The non-transitory computer readable medium of claim 14, wherein the instructions further comprise computer code for obtaining, from the camera, two stereoscopic images at a time. 